RESUMO
A number of neurodevelopmental disorders are caused by defects in activity dependent neuronal plasticity, the process by which neuronal activity shapes developing neuronal circuits. These disorders are caused by genetic mutations or other factors that disrupt intracellular signaling pathways that link the cell surface with the nuclear machinery for gene expression. The signaling pathways disrupted by these disorders are involved in learning, memory and behavior as well as in the synaptic proliferation and pruning that occurs during normal development. Examples of neurodevelopmental disorders that target plasticity include X-linked disorders such as Rett, Fragile-X and Coffin-Lowry Syndromes as well as acquired disorders such as cretinism. Several other X-linked mental retardation syndromes as well as autosomal disorders including neurofibromatosis type 1 and tuberous sclerosis also involve signaling pathways involved in neuronal plasticity. Disruption of neuronal plasticity is a mechanism that may underlie a diverse group of neurodevelopmental disorders.